<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function fn1() {
            let a = 5;
            if(true) {
                let a = 10;
                console.log(a);
            }
            console.log(a);
        }
        fn1()
        function fn2() {
            var a = 5;
            if(true) {
                var a = 10;
                console.log(a);
            }
            console.log(a);
        }
        fn2()
        if(true) {
            function fn3() {
                console.log('fn3---');
            }
        }
        fn3()
    </script>
</body>
</html>